Our invention relates to solid dielectric capacitors, and more specifically to ceramic capacitors such as those of the monolithic, multilayered configuration that are capable of manufacture by cosintering at sufficiently low temperatures to permit the use of base metal electrodes, and to process for the fabrication of such low temperature sintered capacitors. The ceramic capacitors of our invention are particularly notable for their temperature compensating capability, having a practically constant temperature coefficient of capacitance in the normal range of temperatures in which they are intended for use.
We know several conventional ceramic compositions calculated to permit the use of base metal electrodes in the manufacture of monolithic, multilayered ceramic capacitors by cosintering of the base metal electrodes and the dielectric ceramic bodies. Among such known ceramic compositions, and perhaps most pertinent to our present invention, are those described and claimed in Japanese Laid Open Patent Application No. 59-227769, which compositions comprise a major proportion of a primary ingredient expressed by the formula, {(Sr.sub.1-x Ca.sub.x)O}.sub.k TiO.sub.2, and minor proportions of lithium oxide (Li.sub.2 O), silicon dioxide (SiO.sub.2), and one or more of barium oxide (BaO), calcium oxide (CaO), and strontium oxide (SrO). In the manufacture of ceramic capacitors the dielectric bodies of these known compositions are sinterable in a reductive atmosphere, so that electrodes of nickel or like base metal can be employed and buried in the dielectric bodies for cosintering to maturity without the danger of oxidation. The resulting capacitors have a remarkable temperature compensating capability.
However, the temperature compensating capacitors of the above known ceramic composition are unsatisfactory in that their Q factors are less than 4400 when their temperature coefficients of capacitance are in the range of -1000 to +350 parts per million (ppm) per degree centigrade (C.). We have been keenly aware of great demands on temperature compensating ceramic capacitors of higher performance characteristics and smaller size.